Bad framerate and other problems

Ok so i would first post my specs then get down to the real problem:

Now onto the problem at hand.
Basically ive been playing gmod now for 3-5 weeks and for that period of time ive had nothing but problems. First it’s addons; errors, errors and more god damn errors -Fixed that and then now ive come onto the bad framerate; No matter what settings i use; low/high/medium or just basically off altogether, my FPS will always remain below 30 and infact will go to the likings of around 15~'sh so now im building ships in spacebuild and my framerate is awful and its hard positioning props since a slight movement in 15 framerates per second causes a huge stagger and makes it almost impossible. Ive tried to play without SB on a normal construct map and again the FPS is 15.

Next i have the extremely long wait to get into a server, i could sit here and drink a cup of tea and still it the p.ss on load time, like 5 minutes? 5-10 to get into the server. Then you’re met with bad Framerate and yet i havent even got HDR on. My specs allows me to run Call of Duty 4 and MW2 on pretty much high/vhigh detail without a significant FPS drop but those games are graphically more enhanced than the source engine which now brings me back to another problem.

After some time or lets say an hour? maybe 2 hours, everything turns into black and purple checkered boxes, like all the text and pictures, hud etc turn into boxes. Yet i can still see the props and still see reflections (no problem there) and then eventually it’ll stay like that until i quit the game and restart (also effects the game menu). When i use the “camera” tool which hid my UI; My FPS shoots to like 100~'sh without a doubt. I was previously using Depths Inhud but i even deleted that and spared 10~ FPS.

Can someone help me?

Try reinstalling gmod, i mean removing the folder.
And run it WITHOUT addons.

Very well, i will let you know when ive done it.

Edit: Worked: I moved all the addons and expressions i had to another folder and deleted it, then i started an SP and bam it loaded almost instantly with 100~ FPS to spare at very high detail.

Edit2: Tried with just the addons. Again with the looooong load time and bad FPS. Im attempting to remove duplicates and trying again.

One by one add addons that are known well, then add the lesser known ones in later, until you hit the problem.

How many addons do you have?
Have you expoted? (Never heard of exporting? Read this: http://www.facepunch.com/showthread.php?t=688324 )

The problem was i had duplicates of addons. After removing all the duplicates (Had CAF and CustomAddonFrame in the same addons folder) the loading times when 3x faster and i have got 100~ FPS ingame now